I think the knife ending is probably the most jarring, just because it's so out of nowhere.

But god especially after the endings in VLR, the endings in 999 seem really abrupt and inconclusive. With VLR, there are 24 endings total, 13 of which are crappy "game over" endings like the Knife. However 9 are "true" endings based on characters, and those are at least conclusive to some degree most of the time. And then there are the two extra endings that are pretty bizarre and don't really fall into either category.